The objectives of this proposal are to examine and to elucidate those factors and mechanisms involved in the adhesive interactions between circulating polymorphonuclear leukocytes (PMN) and the endothelial lining of blood vessels, occurring under normal conditions and during the acute inflammatory response. The experiments will use as an in vitro model isolated PMN and cultured endothelial cells from various species and organs. Precisely, the goals of this proposal are four-fold: (1) to compare the various types of endothelial cells with respect to the attachment of PMN, morphology, surface characteristics and permeability properties; (2) to determine whether the initial contact between the PMN and endothelium influences subsequent interactions. Is some product(s) released - some molecule expressed on the cell surfaces which will inhibit or enhance the attachment of 'new' PMN to the endothelium? If so, which cell is responsible and which is affected? The characteristics of the effector(s) will be determined using standard biochemical techniques. (3) To determine whether modulation of the lipid composition of endothelial cells can affect the attachment of PMN. Many diseases such as diabetes, atherosclerosis and even chronic alcoholism show altered inflammatory responses, concominant with changes in plasma lipid content. How these changes affect the interaction betwen the PMN and endothelial lining is not known. To examine this question the lipid composition of endothelial cells will be altered using liposomes, fatty acids and alcohol, followed by an investigation of cell functions and morphology. (4) To determine what moieties on the surface of the endothelial cells are responsible for the attachment and specificity of the interactions with PMN. Monoclonal antibodies directed against endothelium will be made and screened for their ability to influence PMN attachment. In addition proteins selectively removed from endothelial cells by differential salt and pH treatments will be chromatographically separated, characterized by polyacrylamide gel electrohoresis and monitored for their effect on neutrophil adhesion. By using a combination of biochemical, biophysical, cell biological and ultrastructural techniques, the events occurring between the PMN and endothelium during the acute inflammatory response will hopefully be better understood and hopefully lead to a means of controlling the acute inflammatory processes.